Systems and devices for anchoring sutures to bone are commonly used in medical or surgical operations. Anchored sutures are typically used to attach soft tissue, such as ligaments, tendons and muscles, to bone or inanimate objects, such as prostheses, to bone. The attachment may hold the tissue to a bone for an extended period of time to allow healing to occur. Alternatively, the attachment may be used to hold tissue in place temporarily during a surgical procedure to help perform or optimize that procedure.
Conventional suture anchors may be inserted into a preformed bore in the bone, driven directly into the bone or driven into the bone in the manner of a common screw, the screw-type anchor being inserted with or without a preformed bore in the bone. U.S. Pat. No. 4,898,156 provides an example of the insertion-type suture anchor. In this example, a suture is attached to the anchor by capturing a knotted end of the suture in the anchor's distally located blind hole, while the free end of the suture exits the anchor by a side slot or an axial through-hole in the anchor body.
An example of the screw-type suture anchor is provided in U.S. Pat. No. 5,156,616. A suture is attached to this anchor by capturing a knotted end of the suture thread in a distal portion of an axial passageway, with the free end of the suture extending proximally through the axial passageway.
Conventional suture anchors for attaching soft tissue to bone often require that a knot be tied in the suture thread in order to attach the suture to the anchor. Such knot tying procedures can be quite difficult and time consuming, especially in closed (e.g. arthroscopic) surgical procedures. It is sometimes desirable to avoid knots and other bulky attachment means because such attachments can irritate tissue in the area in which they are located, and can become loose over time.
Some conventional suture anchors suffer from additional disadvantages as well. Many conventional suture anchors have sharp edges or provide small passageways through which the suture must be threaded, causing difficulties or delays in threading the suture. In some instances, off-axis suture seating or off-axis exit features found on conventional anchors may result in disadvantageous movement or twisting of the anchor after insertion in the bone. Attachment of the suture thread to a distal portion of the anchor may lead to the same disadvantageous movement or twisting.
Moreover, where two free ends of suture thread are required or desired, unwanted tangling and knotting may occur when two suture ends exit the anchor through a single hole in the anchor body or on the same side of the anchor body.
One disadvantage to using screw-type anchor devices is that suture thread can be abraded or otherwise damaged when the anchor is threaded into bone as the suture is disposed between the bone and threads of the anchor. It is thus necessary to drill a hole of larger than desired diameter in the bone in order to prevent any such damage to the suture when the suture anchor is deployed.